Runway threshold lights are essential visual aids located at the beginning of a runway. They help pilots identify the runway's start during takeoff and landing, especially in low visibility conditions. These lights are typically white and are positioned to outline the runway's edges. In addition to their primary function, runway threshold lights can also indicate the runway's status. For instance, when a runway is closed, the lights may change color or be turned off. Proper functioning of these lights is crucial for the safety of aircraft operations at airports, ensuring clear guidance for pilots during critical phases of flight.